The present invention provides an electronic system mounted on an aircraft which can effectively reduce electronic devices and wires by integration of control systems. Specifically, a fuselage (80) of an aircraft (100) is divided into a nose part (80a), a center part (80b), and an aft part (80c), and two IMAs (integrated modular avionics units) (50a to 50c) are provided in each of these parts. The IMA units (50a to 50c) are interconnected via an integrated data bus (53) to construct an integrated electronic system mounted on the aircraft. The system is suitably used for integrating utility systems except for avionics systems, among a plurality of control systems mounted on the aircraft, and is also applicable to integration of the avionics systems.